Technical Field
This disclosure relates to the field of user interface devices and, in particular, to capacitive sensor devices.
Description of the Related Art
The use of a stylus with a touch screen interface is well established. Touchscreen designs have incorporated many different technologies including resistive, capacitive, inductive, and radio frequency sensing arrays. Resistive touch screens, for example, are passive devices well suited for use with a passive stylus. The original PalmPilots® devices from the mid-1990s were one of the first successful commercial devices to utilize a resistive touch screen designed for use with a stylus and helped to popularize that technology. Although resistive touch screens can sense the input from nearly any object, multi-touch is generally not supported. An example of a multi-touch application may be applying two or more fingers to the touch screen. Another example may be inputting a signature, which may include simultaneous palm and stylus input signals. Due to these and other numerous disadvantages, capacitive touch screens are increasingly replacing resistive touch screens in the consumer marketplace.
Various tethered active stylus approaches have been implemented for use with touch screens and are found in many consumer applications such as point-of-sale terminals (e.g., the signature pad used for credit card transactions in retail stores) and other public uses.